1. Technical Field
The present disclosure relates to a power conversion apparatus (power conditioner) and a control method for the power conversion apparatus when an instantaneous voltage drop has occurred in a power system.
2. Description of the Related Art
There has been available a dispersion type power source system including a dispersion type power source, such as a solar cell, and a power conversion apparatus which supplies power generated by the dispersion type power source to a power system.
The power conversion apparatus of the dispersion type power source system generally includes a DC/DC converter and an inverter. The DC/DC converter steps down or up DC power input from the dispersion type power source and supplies the DC power to an internal capacitor. The inverter converts power accumulated in the internal capacitor to AC power.
The dispersion type power source system is expected to continue operation as far as possible in the event of a disturbance, such as an instantaneous voltage drop (hereinafter referred to as an “instantaneous drop”), in a power system and to restore the level of output to a level before the disturbance, when recovering from the disturbance (see Grid-interconnection Code JEAC 9701-2012).
A method for operating a power conversion apparatus during an instantaneous drop is proposed in which an inverter is controlled to fix an output current to a value immediately before the instantaneous drop and a DC/DC converter is controlled such that a voltage of an internal capacitor has a target value set in advance (see, for example, Japanese Unexamined Patent Application Publication No. 2012-55036).